Processes for regenerating a catalyst for the selective conversion of hydrocarbons

ABSTRACT

A catalyst for a selective conversion of hydrocarbons. The catalyst includes a first component selected from the group consisting of Group VIII noble metals and mixtures thereof, a second component selected from the group consisting of alkali metals or alkaline-earth metals and mixtures thereof, and a third component selected from the group consisting of tin, germanium, lead, indium, gallium, thallium and mixtures thereof. The catalyst is a support formed as a spherical catalyst particle with a median diameter between 1.6 mm and 2.5 mm and an apparent bulk density between 0.6 and 0.3 g/cc. Also a process of using such a catalyst for a selective hydrocarbon conversion reaction and a process for regenerating such a catalyst by removing coke from same.

RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent ApplicationSer. No. 62/580,794 filed Nov. 2, 2017, the entirety of which is herebyincorporated by reference.

FIELD OF THE INVENTION

This invention relates generally to a new catalytic material, a processfor the selective conversion of hydrocarbon using the new catalyticmaterial, as well as a process for regenerating the new catalyticmaterial.

BACKGROUND OF THE INVENTION

Petroleum refining and petrochemical processes frequently involve theselective conversion of hydrocarbons with a catalyst. For example, thedehydrogenation of hydrocarbons is an important commercial processbecause of the great demand for dehydrogenated hydrocarbons for themanufacture of various chemical products such as detergents, high octanegasolines, pharmaceutical products, plastics, synthetic rubbers, andother products well known to those skilled in the art. One example ofthis process is dehydrogenating isobutane to produce isobutylene whichcan be polymerized to provide tackifying agents for adhesives,viscosity-index additives for motor oils, impact-resistant andanti-oxidant additives for plastics and a component for oligomerizedgasoline.

The prior art is cognizant of various catalytic composites which containa Group VIII noble metal component, an alkali or alkaline earth metalcomponent, and a component selected from the group consisting of tin,germanium, lead, indium, gallium, thallium, or mixtures thereof. U.S.Pat. Pub. No. 2005/0033101 and U.S. Pat. No. 6,756,340, both assigned tothe present application and the entirety of both which are incorporatedherein by reference, describe various catalysts that are useful,efficient, and effective for the selective conversion of hydrocarbons.

However, there remains an ongoing and continuous need for new catalyticmaterial for selective hydrocarbon conversion processes, especiallythose that improve on one or more characteristics of the known catalyticcompositions.

SUMMARY OF THE INVENTION

The present invention provides a new catalytic material, a process forthe selective conversion of hydrocarbon using the new catalyticmaterial, as well as a process for regenerating the new catalyticmaterial.

Therefore, the present invention may be characterized, in at least oneaspect, as providing a catalyst for a selective conversion ofhydrocarbons comprising: a first component selected from the groupconsisting of Group VIII noble metals and mixtures thereof, a secondcomponent selected from the group consisting of alkali metals oralkaline-earth metals and mixtures thereof, and a third componentselected from the group consisting of tin, germanium, lead, indium,gallium, thallium and mixtures thereof; and a support forming aspherical catalyst particle with a median diameter between 1.6 mm and2.5 mm and an apparent bulk density between 0.6 and 0.3 g/cc.

In at least one other aspect, the present invention may be characterizedas providing a process for the selective conversion of hydrocarbonscomprising: contacting a hydrocarbon at selective conversion conditionswith a catalytic composite a first component selected from the groupconsisting of Group VIII noble metals and mixtures thereof, a secondcomponent selected from the group consisting of alkali metals oralkaline-earth metals and mixtures thereof, and a third componentselected from the group consisting of tin, germanium, lead, indium,gallium, thallium and mixtures thereof and a support forming a sphericalcatalyst particle with a median diameter between 1.6 mm and 2.5 mm andan apparent bulk density between 0.6 and 0.3 g/cc.

In at least another aspect, the present invention may be characterizedas providing a process for regenerating a catalyst used for a selectiveconversion of hydrocarbons comprising: removing coke from a catalyticcomposite a first component selected from the group consisting of GroupVIII noble metals and mixtures thereof, a second component selected fromthe group consisting of alkali metals or alkaline-earth metals andmixtures thereof, and a third component selected from the groupconsisting of tin, germanium, lead, indium, gallium, thallium andmixtures thereof and a support forming a spherical catalyst particlewith a median diameter between 1.6 mm and 2.5 mm and an apparent bulkdensity between 0.6 and 0.3 g/cc.

In yet another aspect, the present invention may be broadlycharacterized as providing a catalyst for a selective conversion ofhydrocarbons, the catalyst comprising: a first component selected fromthe group consisting of Group VIII noble metals and mixtures thereof; asecond component selected from the group consisting of alkali metals oralkaline-earth metals and mixtures thereof, and a third componentselected from the group consisting of tin, germanium, lead, indium,gallium, thallium and mixtures thereof; and a support forming a catalystparticle, the catalyst particle comprising a plurality of pores, amedian diameter between 1.6 mm and 2.5 mm, and an apparent bulk densitybetween 0.6 and 0.3 g/cc, wherein the catalyst particle has an effectivecarbon dioxide diffusivity at 10° C. of at least 1.6×10⁻⁶ m²/sec, or hasan oxygen effective diffusivity at 480° C. of at least 1.5×10⁻⁷ m²/s, orhas both.

In still another aspect, the present invention may be broadlycharacterized as providing a process for the selective conversion ofhydrocarbons by: contacting a hydrocarbon at selective conversionconditions with a catalytic composite comprising a first componentselected from the group consisting of Group VIII noble metals andmixtures thereof, a second component selected from the group consistingof alkali metals or alkaline-earth metals and mixtures thereof, a thirdcomponent selected from the group consisting of tin, germanium, lead,indium, gallium, thallium and mixtures thereof, and a support forming acatalyst particle, the catalyst particle comprising a first plurality ofpores, a median diameter between 1.6 mm and 2.5 mm, and an apparent bulkdensity between 0.6 and 0.3 g/cc, wherein the catalyst particle has aneffective carbon dioxide diffusivity at 10° C. of at least 1.6×10⁻⁶m²/sec, or has an oxygen effective diffusivity at 480° C. of at least1.5×10⁻⁷ m²/s, or has both.

In a further aspect, the present invention may be broadly characterizedas providing a process for reducing a time associated with regeneratinga catalyst used for a selective conversion of hydrocarbons by: removingcoke from a catalyst comprising a first component selected from thegroup consisting of Group VIII noble metals and mixtures thereof, asecond component selected from the group consisting of alkali metals oralkaline-earth metals and mixtures thereof, a third component selectedfrom the group consisting of tin, germanium, lead, indium, gallium,thallium and mixtures thereof, and wherein the time associated withregenerating the catalyst is reduced at least 10% compared to atheoretical time for regenerating the catalyst by the catalyst furthercomprising a support forming a catalyst particle with a median diameterbetween 1.6 mm and 2.5 mm and an apparent bulk density between 0.6 and0.3 g/cc.

In another further aspect, the present invention may be broadlycharacterized as providing a process for regenerating a catalyst usedfor a selective conversion of hydrocarbons by: removing coke from acatalytic composite a first component selected from the group consistingof Group VIII noble metals and mixtures thereof, a second componentselected from the group consisting of alkali metals or alkaline-earthmetals and mixtures thereof, and a third component selected from thegroup consisting of tin, germanium, lead, indium, gallium, thallium andmixtures thereof and a support forming a catalyst particle with a mediandiameter between 1.6 mm and 2.5 mm and an apparent bulk density between0.6 and 0.3 g/cc, and wherein a time associated with removing coke fromthe catalytic composite is lower than a calculated time to remove cokefrom the catalytic composite.

In still yet another aspect, the present invention may be broadlycharacterized as providing a system comprising: at least one processor;at least one memory storing computer-executable instructions; and atleast one receiver configured to receive data of an apparatus or streamof a process for the conversion of hydrocarbons, an apparatus or streamin fluid communication with and upstream to the conversion ofhydrocarbons, an apparatus or stream in fluid communication with anddownstream from the conversion of hydrocarbons, or any combinationthereof, where the process for the conversion of hydrocarbons comprisesa catalytic composite comprising a first component selected from thegroup consisting of Group VIII noble metals and mixtures thereof, asecond component selected from the group consisting of alkali metals oralkaline-earth metals and mixtures thereof, a third component selectedfrom the group consisting of tin, germanium, lead, indium, gallium,thallium and mixtures thereof, and a support forming a catalystparticle, the catalyst particle comprising a plurality of pores, amedian diameter between 1.6 mm and 2.5 mm, an apparent bulk densitybetween 0.6 and 0.3 g/cc, wherein the catalyst particle has an effectivecarbon dioxide diffusivity at 10° C. of at least 1.6×10⁻⁶ m²/sec, or hasan oxygen effective diffusivity at 480° C. of at least 1.5×10⁻⁷ m²/s, orhas both.

In another further aspect, the present invention may be broadlycharacterized as providing a method for receiving data of a process forthe selective conversion of hydrocarbons, the method comprisingreceiving data from at least one sensor of a process comprising:contacting a hydrocarbon at selective conversion conditions with acatalytic composite comprising a first component selected from the groupconsisting of Group VIII noble metals and mixtures thereof, a secondcomponent selected from the group consisting of alkali metals oralkaline-earth metals and mixtures thereof, a third component selectedfrom the group consisting of tin, germanium, lead, indium, gallium,thallium and mixtures thereof, and a support forming a catalystparticle, the catalyst particle comprising a plurality of pores, amedian diameter between 1.6 mm and 2.5 mm, and an apparent bulk densitybetween 0.6 and 0.3 g/cc, wherein the catalyst particle has an effectivecarbon dioxide diffusivity at 10° C. of at least 1.6×10⁻⁶ m²/sec, or hasan oxygen effective diffusivity at 480° C. of at least 1.5×10⁻⁷ m²/s, orhas both.

Additional aspects, embodiments, and details of the invention, all ofwhich may be combinable in any manner, are set forth in the followingdetailed description of the invention.

DETAILED DESCRIPTION OF THE DRAWINGS

One or more exemplary embodiments of the present invention will bedescribed below in conjunction with the following drawing figures, inwhich:

FIG. 1 shows a graph plotting propane conversion versus total hours onstream for a catalyst according to the present invention compared withthree prior art catalysts;

FIG. 2 shows a graph plotting measured carbon dioxide effectivediffusivities versus average pore diameter for a catalyst according tothe present invention compared with two prior art catalysts;

FIG. 3 shows a graph plotting time to 85% carbon burn off versusmeasured coke amounts for the catalysts in FIG. 2; and,

FIG. 4 shows a graph plotting calculated oxygen effective diffusivitiesversus average pore diameter for a catalyst according to the presentinvention compared with two prior art catalysts.

DETAILED DESCRIPTION OF THE INVENTION

As mentioned above, a new catalytic material, a process for theselective conversion of hydrocarbon using the new catalytic material, aswell as a process for regenerating the new catalytic material have beeninvented. The new catalytic material includes low density supportmaterial with large pore volume, large porosity, and large porediameter. The lower density offers several advantages, especially in adiffusion limited reaction. Specifically, this combination of propertiesprovides the new catalytic material with the support high effectivediffusivity which leads to improved performance and regeneration (i.e.,coke burn) benefits. Additionally, the new catalytic material has higherpiece crush strength, potentially leading to less fines produced in thereactor. In addition, the new catalytic material offers the possibilityof increasing the throughput for the reactor. This is believed to allowfor a higher mass flow through the unit. Additionally, the bed deltapressure is lower for the new catalytic material, allowing for anextended run length in between screen cleanings (longer time until thepressure builds up to the same level as in a smaller pill catalyst bed).

Apart from the advantages associated with the use of the new catalyticcomposition for the selective conversion of hydrocarbons, the newcomposition also provides superior and unexpected results associatedwith regeneration of the spent catalyst. The calculated predicted burnrate differences between current catalysts, and the new catalystmaterial, taking into account the different diameters, suggest that forthe new catalyst material it should take 27% longer for the carbon toburn compared to conventional catalysts. However, even though the newcatalyst material is larger, the new catalytic material of thisinvention had the shortest coke burn time and highest effectivediffusivities despite the large pill diameter and long diffusion pathscompared to conventional catalysts because of the lower density andconsequently the improved porosity, pore volume, pore diameter.

With these general principles in mind, one or more embodiments of thepresent invention will be described with the understanding that thefollowing description is not intended to be limiting.

As mentioned above, an essential feature of the present invention liesin the characteristics of the support for the instant catalyst.Specifically, according to various aspects of the present invention, itis important that the support have a median diameter between 1.6 mm and2.5 mm and an apparent bulk density (ABD) between 0.6 and 0.3 g/cc. Themedian diameter is preferably between 1.8 and 2.2 mm, and mostpreferably 1.8 mm. The ABD is less than 0.6, preferably between 0.6 to0.5 g/cc, most preferably between 0.57 and 0.52 g/cc. Additionally,and/or alternatively, it is important for the support to have an averagepore diameter between 200 to 350 Angstroms, a porosity of at least 75%,and an ABD between 0.60 and 0.3 g/cc. The ABD may further be between 0.6and 0.5 g/cc, preferably between 0.57 to 0.52 g/cc, for example the ABDmay be 0.57 g/cc. The average pore diameter may further between 240 to300, or 240 to 280, Angstroms, including any smaller range within thesevalues. Further, the porosity may be between 75% and 85% and may be anyvalue therebetween, or a range made from valves selected between any ofthe ranges, for example at least 80%. In either embodiment, the lowerdensity support offers advantages when used in a diffusion limitedreaction—such as the dehydrogenation of propane—in comparison to similardehydrogenation catalysts of the prior art. Additionally, a catalystwith the lower density support has surprisingly shown improved coke burnbenefits.

The median diameter of the particles was measured via the Dynamic ImageAnalysis using a CAMSIZER®. Two cameras capture a continuous series ofimages of particles as they pass in front of an LED panel. The imagesare processed in real-time using the size and shape parameters definedin the software.

In order to measure the ABD, the substance is put into a receiver ofknown dimensions and weight. The International Standard ISO 697distinguishes two types for the determination of apparent bulk density.The basically differ in the size of the receivers used. The instrumentsfor the determination of apparent density imply a lockable funnel offixed dimensions, a receiver and a stand that holds them together in adefined position. The funnel is then filled with the sample of powder orgranule then opened. The sample then flows into the receiver with theknown volume and the apparent density is obtained by weighing thereceiver.

The porosity, the pore diameters, and the total intrusion volumes weremeasured using method UOP 578-11 Automated Pore Size Distribution ofPorous Substances by Mercury Porosimetry. The volume change in a mercurycolumn was monitored while being subjected to a constant appliedpressure from sub ambient to 60,000 psi. The measurement was conductedin both intrusion and extrusion modes.

Returning to the catalytic materials of the present invention, thesupport comprises a number of catalytic components including a GroupVIII noble metal component, an alkali or alkaline earth component, and acomponent selected from the group consisting of tin, germanium, lead,indium, gallium, thallium, or mixtures thereof.

The Group VIII noble metal may be selected from the group consisting ofplatinum, palladium, iridium, rhodium, osmium, ruthenium, or mixturesthereof. Platinum, however, is the preferred Group VIII noble metalcomponent. Preferably the Group VIII noble metal component is welldispersed throughout the catalyst. It generally will comprise about 0.01to 5 wt. %, calculated on an elemental basis, of the final catalyticcomposite. Preferably, the catalyst comprises about 0.1 to 2.0 wt. %Group VIII noble metal component, especially about 0.1 to about 2.0 wt.% platinum.

The Group VIII noble metal component may be incorporated in thecatalytic composite in any suitable manner such as, for example, bycoprecipitation or cogelation, ion exchange or impregnation, ordeposition from a vapor phase or from an atomic source or by likeprocedures either before, while, or after other catalytic components areincorporated. The preferred method of incorporating the Group VIII noblemetal component is to impregnate the alumina support with a solution orsuspension of a decomposable compound of a Group VIII noble metal. Forexample, platinum may be added to the support by commingling the latterwith an aqueous solution of chloroplatinic acid. Another acid, forexample, nitric acid or other optional components, may be added to theimpregnating solution to further assist in evenly dispersing or fixingthe Group VIII noble metal component in the final catalyst composite.

The alkali or alkaline earth component of the present invention may beselected from the group consisting of cesium, rubidium, potassium,sodium, and lithium or from the group consisting of barium, strontium,calcium, and magnesium or mixtures of metals from either or both ofthese groups. Potassium is the preferred second catalytic component. Itis believed that the alkali and alkaline earth component exists in thefinal catalytic composite in an oxidation state above that of theelemental metal. The alkali and alkaline earth component may be presentas a compound such as the oxide, for example, or combined with thecarrier material or with the other catalytic components. Preferably thealkali and alkaline earth component is well dispersed throughout thecatalytic composite. The alkali or alkaline earth component willpreferably comprise between 0.7 and 1.5 wt. %, or between 0.85 to 1.1wt. %, calculated on an elemental basis of the final catalyticcomposite.

The alkali or alkaline earth component may be incorporated in thecatalytic composite in any suitable manner such as, for example, bycoprecipitation or cogelation, by ion exchange or impregnation, or bylike procedures either before, while, or after other catalyticcomponents are incorporated. A preferred method of incorporating thealkali component is to impregnate the carrier material with a solutionof potassium hydroxide.

The third component of the catalyst of the present invention is amodifier metal component selected from the group consisting of tin,germanium, lead, indium, gallium, thallium, and mixtures thereof. Theeffective amount of the third modifier metal component is preferablyuniformly impregnated. Generally, the catalyst will comprise from about0.01 to about 10 wt. % of the third modifier metal component calculatedon an elemental basis on the weight of the final composite. Preferably,the catalyst will comprise from about 0.1 to about 5 wt. % of the thirdmodifier metal component. The third modifier metal component of thepresent invention preferably is tin. Some or all of the tin componentmay be present in the catalyst in an oxidation state above that of theelemental metal. This component may exist within the composite as acompound such as the oxide, sulfide, halide, oxychloride, aluminate,etc., or in combination with the carrier material or other ingredientsof the composite. Preferably, the tin component is used in an amountsufficient to result in the final catalytic composite containing, on anelemental basis, about 0.01 to about 10 wt. % tin, with best resultstypically obtained with about 0.1 to about 5 wt. % tin.

The third component of the catalyst may be composited with the supportin any sequence. Thus, the first or second component may be impregnatedon the support followed by sequential surface or uniform impregnation ofthe third component. Alternatively, the third component may be surfaceor uniformly impregnated on the support followed by impregnation of theother catalytic component.

The catalytic composite of this invention may also contain a halogencomponent. The halogen component may be fluorine, chlorine, bromine, oriodine, or mixtures thereof. Chlorine is the preferred halogencomponents. The halogen component is generally present in a combinedstate with the porous carrier material and alkali component. Preferably,the halogen component is well dispersed throughout the catalyticcomposite. The halogen component may comprise from more than 0.01 wt. %to about 15 wt. %, calculated on an elemental basis, of the finalcatalytic composite.

The halogen component may be incorporated in the catalytic composite inany suitable manner, either during the preparation of the carriermaterial or before, while, or after other catalytic components areincorporated. For example, the alumina sol utilized to form thepreferred aluminum carrier material may contain halogen and thuscontribute at least some portion of the halogen content in the finalcatalyst composite. Also, the halogen component or a portion thereof maybe added to the catalyst composite during the incorporation of thecarrier material with other catalyst components, for example, by usingchloroplatinic acid to impregnate the platinum component. The halogencomponent or a portion thereof may also be added to the catalystcomposite by contacting the catalyst with the halogen or a compound orsolution containing the halogen before or after other catalystcomponents are incorporated with the carrier material. Suitablecompounds containing the halogen include acids containing the halogen,for example, hydrochloric acid. Or, the halogen component or a portionthereof may be incorporated by contacting the catalyst with a compoundor solution containing the halogen in a subsequent catalystregeneration.

In regeneration, carbon deposited on the catalyst as coke during use ofthe catalyst in a hydrocarbon conversion process is burned off and thecatalyst and the platinum group component on the catalyst isredistributed to provide a regenerated catalyst with performancecharacteristics much like the fresh catalyst. The halogen component maybe added during the carbon burn step or during the platinum groupcomponent redistribution step, for example, by contacting the catalystwith a hydrogen chloride gas. Also, the halogen component may be addedto the catalyst composite by adding the halogen or a compound orsolution containing the halogen, such as propylene dichloride, forexample, to the hydrocarbon feed stream or to the recycle gas duringoperation of the hydrocarbon conversion process. The halogen may also beadded as chlorine gas (Cl₂).

The carrier material of the present invention is alumina having thecharacteristics discussed above. The alumina carrier material may beprepared in any suitable manner from synthetic or naturally occurringraw materials. The carrier may be formed in any desired shape such asspheres, pills, cakes, extrudates, powders, granules, etc., and it maybe utilized in any particle size. A preferred shape of alumina is thesphere. Additionally, the carrier material can be mono-modal, bi-modal,or a mixture thereof.

To make alumina spheres, aluminum metal is converted into an alumina solby reacting it with a suitable peptizing agent and water, and thendropping a mixture of the sol into an oil bath to form sphericalparticles of the alumina gel. It is also an aspect of this inventionthat the third modifier metal component may be added to the alumina solbefore it is reacted with a peptizing agent and dropped into the hot oilbath. Other shapes of the alumina carrier material may also be preparedby conventional methods. After the alumina particles optionallycontaining the co-formed third component are shaped, they are dried andcalcined.

It is preferable that the final calcination step be at conditionssufficient to convert the alumina into theta-alumina which conforms tothe desired characteristics of the alumina base of the instant catalyst.Such conditions would include a calcination temperature closelycontrolled between 950° and 1100° C. and preferably from 975° to 1050°C.

It is preferred that the alumina component is essentially theta-alumina.By “essentially theta-alumina”, it is meant that at least 75% of thealumina crystallites are theta-alumina crystallites. The remainingcrystallites of alumina will likely be in the form of gamma-alumina.However, other forms of alumina crystallites known in the art may alsobe present. It is most preferred if the essentially theta-aluminacomponent comprises at least 90% crystallites of theta-alumina.

As explained, the theta-alumina form of crystalline alumina is producedfrom the amorphous alumina precursor by closely controlling the maximumcalcination temperature experienced by the catalyst support. Calcinationtemperatures ranging from 800° to 950° C. are known to produce aluminacomprising essentially crystallites of gamma-alumina. Calcinationtemperatures of 1100° C. and above are known to promote the formation ofalpha-alumina crystallites while temperatures of from 950° to 1100° C.and especially from 975° to 1050° C. promote the formation oftheta-alumina crystallites.

After the catalyst components have been combined with the desiredalumina support, the resulting catalyst composite will generally bedried at a temperature of from about 100° to about 320° C. for a periodof typically about 1 to 24 hours or more and thereafter calcined at atemperature of about 320° to about 600° C. for a period of about 0.5 toabout 10 or more hours. Typically, chlorine-containing compounds areadded to air to prevent sintering of catalyst metal components. Thisfinal calcination typically does not affect the alumina crystallites orABD. However, the high temperature calcination of the support may beaccomplished at this point if desired. Finally, the calcined catalystcomposite is typically subjected to a reduction step before use in thehydrocarbon conversion process. This reduction step is effected at atemperature of about 230° to about 650° C. for a period of about 0.5 toabout 10 or more hours in a reducing environment, preferably dryhydrogen, the temperature and time being selected to be sufficient toreduce substantially all of the platinum group component to theelemental metallic state.

According to one or more embodiments, the catalyst composition is usedin a hydrocarbon conversion process, such as dehydrogenation. In thepreferred process, dehydrogenatable hydrocarbons are contacted with thecatalytic composition of the present invention in a dehydrogenation zonemaintained at dehydrogenation conditions. This contacting may beaccomplished in a fixed catalyst bed system, a moving catalyst bedsystem, a fluidized bed system, etc., or in a batch-type operation. Afixed bed system is preferred in one preferred embodiment. In this fixedbed system, the hydrocarbon feed stream is preheated to the desiredreaction temperature and then passed into the dehydrogenation zonecontaining a fixed bed of the catalyst. The dehydrogenation zone mayitself comprise one or more separate reaction zones with heating meanstherebetween to ensure that the desired reaction temperature can bemaintained at the entrance to each reaction zone. The hydrocarbon may becontacted with the catalyst bed in either upward, downward, or radialflow fashion. Radial flow of the hydrocarbon through the catalyst bed ispreferred for commercial scale reactors. The hydrocarbon may be in theliquid phase, a mixed vapor-liquid phase, or the vapor phase when itcontacts the catalyst.

Hydrocarbons which may be dehydrogenated include dehydrogenatablehydrocarbons having from 2 to 30 or more carbon atoms includingparaffins, alkylaromatics, naphthenes, and olefins. One group ofhydrocarbons which can be dehydrogenated with the catalyst is the groupof normal paraffins having from 2 to 30 or more carbon atoms. Thecatalyst is particularly useful for dehydrogenating paraffins havingfrom 2 to 15 or more carbon atoms to the corresponding monoolefins orfor dehydrogenating monoolefins having from 3 to 15 or more carbon atomsto the corresponding diolefins. The catalyst is especially useful in thedehydrogenation of C2-C6 paraffins, primarily propane and butanes, tomonoolefins.

Dehydrogenation conditions include a temperature of from about 400° toabout 900° C., a pressure of from about 0.01 to 10 atmospheres absolute,and a liquid hourly space velocity (LHSV) of from about 0.1 to 100 hr⁻¹.Generally, for normal paraffins, the lower the molecular weight, thehigher the temperature required for comparable conversion. The pressurein the dehydrogenation zone is maintained as low as practicable,consistent with equipment limitations, to maximize the chemicalequilibrium advantages.

The effluent stream from the dehydrogenation zone generally will containunconverted dehydrogenatable hydrocarbons, hydrogen, and the products ofdehydrogenation reactions. This effluent stream is typically cooled andpassed to a hydrogen separation zone to separate a hydrogen-rich vaporphase from a hydrocarbon-rich liquid phase. Generally, thehydrocarbon-rich liquid phase is further separated by means of either asuitable selective adsorbent, a selective solvent, a selective reactionor reactions, or by means of a suitable fractionation scheme.Unconverted dehydrogenatable hydrocarbons are recovered and may berecycled to the dehydrogenation zone. Products of the dehydrogenationreactions are recovered as final products or as intermediate products inthe preparation of other compounds.

The dehydrogenatable hydrocarbons may be admixed with a diluent materialbefore, while, or after being passed to the dehydrogenation zone. Thediluent material may be hydrogen, steam, methane, ethane, carbondioxide, nitrogen, argon, and the like or a mixture thereof. Hydrogenand steam are the preferred diluents. Ordinarily, when hydrogen or steamis utilized as the diluent, it is utilized in amounts sufficient toensure a diluent-to-hydrocarbon mole ratio of about 0.1:1 to about 40:1,with best results being obtained when the mole ratio range is about0.4:1 to about 10:1. The diluent stream passed to the dehydrogenationzone will typically be recycled diluent separated from the effluent fromthe dehydrogenation zone in a separation zone.

A combination of diluents, such as steam with hydrogen, may be employed.When hydrogen is the primary diluent water or a material whichdecomposes at dehydrogenation conditions to form water such as analcohol, aldehyde, ether, or ketone, for example, may be added to thedehydrogenation zone, either continuously or intermittently, in anamount to provide, calculated on the basis of equivalent water, about 1to about 20,000 weight ppm of the hydrocarbon feed stream. About 1 toabout 10,000 weight ppm of water addition gives best results whendehydrogenating paraffins have from 6 to 30 or more carbon atoms.

To be commercially successful, a dehydrogenation catalyst should exhibitthree characteristics, namely, high activity, high selectivity, and goodstability. Activity is a measure of the catalyst's ability to convertreactants into products at a specific set of reaction conditions, thatis, at a specified temperature, pressure, contact time, andconcentration of diluent such as hydrogen, if any. For dehydrogenationcatalyst activity, the conversion or disappearance of paraffins inpercent relative to the amount of paraffins in the feedstock ismeasured. Selectivity is a measure of the catalyst's ability to convertreactants into the desired product or products relative to the amount ofreactants converted. For catalyst selectivity, the amount of olefins inthe product, in mole percent, relative to the total moles of theparaffins converted is measured. Stability is a measure of the rate ofchange with time on stream of the activity and selectivityparameters—the smaller rates implying the more stable catalysts.

The dehydrogenation of hydrocarbons is an endothermic process. In asystem employing a dehydrogenation catalyst only, it is typicallynecessary to add superheated steam at various points in the process orto intermittently remove and reheat the reaction stream between catalystbeds. Some processes have been developed which utilize a two-catalystsystem with distinct beds or reactors of dehydrogenation or selectiveoxidation catalysts. The purpose of the selective oxidation catalysts isto selectively oxidize the hydrogen produced as a result of thedehydrogenation reaction with oxygen that had been added to theoxidation zone to generate heat internally in the process. The heatgenerated typically is sufficient to cause the reaction mixture to reachdesired dehydrogenation temperatures for the next dehydrogenation step.The instant process may be accomplished in this previously mentionedsystem. If such a process is employed, the instant catalyst wouldcomprise at least the dehydrogenation catalyst with another specificcatalyst being used to accomplish the oxidation reaction.

The selective oxidation step, if utilized, uses the hydrogen which hasbeen produced in the dehydrogenation step of the process to supply heatto the next dehydrogenation reaction section. To accomplish this, anoxygen-containing gas is first introduced into the reactor, preferablyat a point adjacent to the selective oxidative catalyst section. Theoxygen in the oxygen-containing gas is necessary to oxidize the hydrogencontained in the reaction stream. Examples of oxygen-containing gaseswhich may be utilized to effect the selective oxidation of the hydrogenwhich is present will include air, oxygen, or air or oxygen diluted withother gases such as steam, carbon dioxide and inert gases such asnitrogen, argon, helium, etc. The amount of oxygen which is introducedto contact the process stream may range from about 0.01:1 to about 2:1moles of oxygen per mole of hydrogen contained in the process stream atthe point where oxygen is added to the process stream. In the selectiveoxidation reaction, the process stream which comprises unreacteddehydrogenatable hydrocarbon, dehydrogenated hydrocarbon, and hydrogenis reacted with oxygen in the presence of the selective steamoxidation/dehydrogenation catalyst whereby hydrogen is selectivelyoxidized to produce water and heat energy with very little of the oxygenreacting with the hydrocarbons.

The selective steam oxidation/dehydrogenation catalyst may be one thatis useful for the selective oxidation of hydrogen in the presence ofhydrocarbons. An example of such a catalyst is disclosed in U.S. Pat.No. 4,418,237. Alternatively, the catalyst used for the selectiveoxidation step may be identical to the catalyst utilized for thedehydrogenation step. Such catalysts or processes for their use aredisclosed in U.S. Pat. Nos. 4,613,715 and 3,670,044.

The oxygen-containing reactant may be added to the instant process invarious ways such as by admixing oxygen with a relatively coolhydrocarbon feed stream or with the steam diluent, or it may be addeddirectly to the reactor independently of the feed hydrocarbons or thesteam diluent. In addition, the oxygen-containing reactant can be addedat one or more points in the reactor in such a fashion as to minimizelocal concentrations of oxygen relative to hydrogen in order todistribute the beneficial temperature rise produced by the selectivehydrogen oxidation over the entire length of the reaction zone. The useof multiple injection points minimizes the opportunity for localbuild-up of the concentration of oxygen relative to the amount ofhydrogen, thereby minimizing the opportunity for undesired reaction ofthe oxygen-containing gas with either feed or product hydrocarbons.

The following example is introduced to further describe the catalyst andprocess of the invention. This example is intended as an illustrativeembodiment and should not be considered to restrict the otherwise broadinterpretation of the invention as set forth in the claims appendedhereto.

EXAMPLES

Propane Dehydrogenation

In order to demonstrate the advantages to be achieved by the presentinvention, a catalyst of this invention and three state-of-the-artcatalysts were prepared.

The first prior art catalyst (Catalyst A) contained a median porediameter of 1.6 mm with an ABD of 0.62 g/cc. The second prior artcatalyst (Catalyst B) contained a median pore diameter of 1.8 mm with anABD of 0.63 g/cc. The third prior art catalyst (Catalyst C) contained amedian pore diameter of 1.8 mm and ABD of 0.62 g/cc. The catalystaccording to the present invention (Catalyst D) contained a median porediameter of 1.8 mm and an ABD of 0.56 g/cc. All of these catalysts hadthe same amount (approximately) of platinum, tin, and potassium on avolumetric level. The properties of the catalysts are presented in Table1 for comparison and the results of the testing are shown in FIG. 1.

TABLE 1 Cata- Cata- Cata- Cata- lyst A lyst B lyst C lyst D ABD (g/cc)0.62 0.63 0.62 0.56 Median Diameter (mm) 1.6 1.8 1.8 1.8 BET SurfaceArea (m2/g) 86 81 82 85 Total Hg Intrusion 0.79 0.74 0.77 0.89 volume(cc/g) Median Pore Diameter 239 237 113 277 (Hg) (Å) Porosity 79.7 7080.9 82.6 Diffusivity 1.67E−6 n/a 1.46E−6 2.13E−6 (avg.) Maximum Propane16.7 15.9 16.6 17.5 Conversion Propane Conversion Slope −0.20 −0.25−0.25 −0.21

The diffusivity was measured at 10° C. with a Kinetic Testing Unit (KTU)using carbon dioxide as the probe molecule. The values obtained from theKTU are shown in FIG. 2.

Each catalyst (approximately 15 cc) was tested in a pilot plant todehydrogenate propane to produce propylene for 20 hours on stream (HOS).The operating conditions of each pilot plant test included a feed with77% propane and 23% (by weight) propylene, and a hydrogen to feed ratioof 0.7, a liquid hourly space velocity (LHSV) of 30 hr⁻¹, a pressure of135 kPa (5 psig), a feed temperature of 650° C. (1202° F.), and 70 ppmof hydrogen sulfide. The results of the tests are reflected in FIG. 1demonstrating the propane conversion plotted against the total hours onstream.

From FIG. 1, it can be seen that the catalyst of the present invention(Catalyst D) demonstrates the highest initial maximum activity andmaintains a higher propane conversion to 20 hours on stream than theprior art catalysts at the same operating conditions.

Spent Catalyst Regeneration (Coke Burn)

Catalysts A, C, and D from the foregoing propane dehydrogenation wereanalyzed after being taken off stream. The spent catalyst particles wereanalyzed via thermogravimetric analysis (TGA).

For the TGA, 50 mg (approximately 14-20 catalyst particles) werepretreated to desorb volatile substances at 550° C. in nitrogen gas.After the pretreatment, two temperature measurements were used. Thecatalyst particles were either cooled to 480° C. or held at 550° C. and1% oxygen gas was added to the flowing nitrogen gas to burn off the cokethat had been formed on the catalyst. The TGA data was processed usingthe shell progressive diffusion model to calculate the coke burn timeand the Oxygen Effective Diffusivities. The results of the 480° C. TGAprocessed data are shown in FIG. 3 and the calculated OxygenDiffusivities are shown in the below TABLE 2 and FIG. 4.

TABLE 2 Burn Median Pore Oxygen Temperature Diameter (Hg), (Å)Diffusivity (m²/s) Catalyst D 480° C. 257  2.6E−7 Catalyst A 480° C. 222 1.42E−7 Catalyst A 480° C. 222 1.469E−7 Catalyst A 480° C. 222 1.845E−7Catalyst A 480° C. 222 1.516E−7 Catalyst C 480° C. 115 7.471E−8 CatalystC 480° C. 115 1.264E−7 Catalyst D 550° C. 257 8.376E−7 Catalyst A 550°C. 222 5.447E−7 Catalyst A 550° C. 222 5.588E−7 Catalyst A 550° C. 2225.578E−7 Catalyst C 550° C. 115 2.079E−7 Catalyst C 550° C. 115 3.152E−7

From FIGS. 3 and 4, it can be seen that the catalyst of the presentinvention (Catalyst D) demonstrates the shortest coke burn time and thehighest oxygen effective diffusivities. This is surprising andunexpected given the large particle diameter and long diffusion paths.Indeed, initial calculations indicated that Catalyst D would have 27%longer burn time. However, as shown in FIG. 3, Catalyst D actually hadan 18% shorter burn off time compared to Catalyst A, and at least a 50%shorter burn time compared to Catalyst C. Thus, not only does thepresent catalytic composition provide superior results for the selectivehydrocarbon conversion process, it also has superior and unexpectedresults associated with regeneration.

Any of the above lines, conduits, units, devices, vessels, surroundingenvironments, zones or similar may be equipped with one or moremonitoring components including sensors, measurement devices, datacapture devices or data transmission devices. Signals, process or statusmeasurements, and data from monitoring components may be used to monitorconditions in, around, and on process equipment. Signals, measurements,and/or data generated or recorded by monitoring components may becollected, processed, and/or transmitted through one or more networks orconnections that may be private or public, general or specific, director indirect, wired or wireless, encrypted or not encrypted, and/orcombination(s) thereof; the specification is not intended to be limitingin this respect.

Signals, measurements, and/or data generated or recorded by monitoringcomponents may be transmitted to one or more computing devices orsystems. Computing devices or systems may include at least one processorand memory storing computer-readable instructions that, when executed bythe at least one processor, cause the one or more computing devices toperform a process that may include one or more steps. For example, theone or more computing devices may be configured to receive, from one ormore monitoring component, data related to at least one piece ofequipment associated with the process. The one or more computing devicesor systems may be configured to analyze the data. Based on analyzing thedata, the one or more computing devices or systems may be configured todetermine one or more recommended adjustments to one or more parametersof one or more processes described herein. The one or more computingdevices or systems may be configured to transmit encrypted orunencrypted data that includes the one or more recommended adjustmentsto the one or more parameters of the one or more processes describedherein.

SPECIFIC EMBODIMENTS

While the following is described in conjunction with specificembodiments, it will be understood that this description is intended toillustrate and not limit the scope of the preceding description and theappended claims.

A first embodiment of the invention is a process for reducing a timeassociated with regenerating a catalyst used for a selective conversionof hydrocarbons, the process comprising removing coke from a catalystcomprising a first component selected from the group consisting of GroupVIII noble metals and mixtures thereof, a second component selected fromthe group consisting of alkali metals or alkaline-earth metals andmixtures thereof, a third component selected from the group consistingof tin, germanium, lead, indium, gallium, thallium and mixtures thereof,and wherein the time associated with regenerating the catalyst isreduced at least 10% compared to a theoretical time for regenerating thecatalyst by the catalyst further comprising a support forming a catalystparticle with a median diameter between 1.6 mm and 2.5 mm and anapparent bulk density between 0.6 and 0.3 g/cc. An embodiment of theinvention is one, any or all of prior embodiments in this paragraph upthrough the first embodiment in this paragraph wherein the apparent bulkdensity is between 0.6 and 0.5 g/cc. An embodiment of the invention isone, any or all of prior embodiments in this paragraph up through thefirst embodiment in this paragraph wherein the median diameter isbetween 1.8 mm and 2.2 mm. An embodiment of the invention is one, any orall of prior embodiments in this paragraph up through the firstembodiment in this paragraph wherein the median diameter is between 1.8mm and 2.2 mm. An embodiment of the invention is one, any or all ofprior embodiments in this paragraph up through the first embodiment inthis paragraph wherein the apparent bulk density is between 0.57 to 0.52g/cc. An embodiment of the invention is one, any or all of priorembodiments in this paragraph up through the first embodiment in thisparagraph wherein the median diameter is 1.8 mm. An embodiment of theinvention is one, any or all of prior embodiments in this paragraph upthrough the first embodiment in this paragraph wherein the apparent bulkdensity is 0.57 g/cc. An embodiment of the invention is one, any or allof prior embodiments in this paragraph up through the first embodimentin this paragraph wherein the catalyst has mono-modal porousdistribution. An embodiment of the invention is one, any or all of priorembodiments in this paragraph up through the first embodiment in thisparagraph wherein the catalyst has bi-modal porous distribution. Anembodiment of the invention is one, any or all of prior embodiments inthis paragraph up through the first embodiment in this paragraphwherein, the first component is platinum, the second component ispotassium, and the third component is tin. An embodiment of theinvention is one, any or all of prior embodiments in this paragraph upthrough the first embodiment in this paragraph wherein the support isselected from the group consisting of silica, alumina, silica-alumina, azeolite, a non-zeolitic molecular sieve, titania, zirconia and mixturesthereof. An embodiment of the invention is one, any or all of priorembodiments in this paragraph up through the first embodiment in thisparagraph wherein the support is selected from the group consisting oftheta-alumina, gamma-alumina, eta-alumina, delta-alumina, and mixturesthereof. An embodiment of the invention is one, any or all of priorembodiments in this paragraph up through the first embodiment in thisparagraph wherein the noble metal is in an amount between 0.01 wt. % and5 wt. % based on the total weight. An embodiment of the invention isone, any or all of prior embodiments in this paragraph up through thefirst embodiment in this paragraph wherein the second component is in anamount between 0.7 wt. % and 1.5 wt. % based on the total weight. Anembodiment of the invention is one, any or all of prior embodiments inthis paragraph up through the first embodiment in this paragraph whereinthe third component is in an amount between 0.01 wt. % and 5 wt. % basedon the total weight. An embodiment of the invention is one, any or allof prior embodiments in this paragraph up through the first embodimentin this paragraph wherein the catalyst particle is spherical. Anembodiment of the invention is one, any or all of prior embodiments inthis paragraph up through the first embodiment in this paragraph whereinthe catalyst has an oxygen effective diffusivity at 480° C. of at least1.5×10⁻⁷ m₂/s. An embodiment of the invention is one, any or all ofprior embodiments in this paragraph up through the first embodiment inthis paragraph wherein the catalyst particle has an effective carbondioxide diffusivity at 10° C. of at least 1.6×10⁻⁶ m²/sec.

A second embodiment of the invention is a process for regenerating acatalyst used for a selective conversion of hydrocarbons, the processcomprising removing coke from a catalytic composite a first componentselected from the group consisting of Group VIII noble metals andmixtures thereof, a second component selected from the group consistingof alkali metals or alkaline-earth metals and mixtures thereof, and athird component selected from the group consisting of tin, germanium,lead, indium, gallium, thallium and mixtures thereof and a supportforming a catalyst particle with a median diameter between 1.6 mm and2.5 mm and an apparent bulk density between 0.6 and 0.3 g/cc, andwherein a time associated with removing coke from the catalyticcomposite is lower than a calculated time to remove coke from thecatalytic composite.

A third embodiment of the invention is a catalyst for a selectiveconversion of hydrocarbons, the catalyst comprising a first componentselected from the group consisting of Group VIII noble metals andmixtures thereof, a second component selected from the group consistingof alkali metals or alkaline-earth metals and mixtures thereof, and athird component selected from the group consisting of tin, germanium,lead, indium, gallium, thallium and mixtures thereof; and a supportforming a spherical catalyst particle with a median diameter between 1.6mm and 2.5 mm and an apparent bulk density between 0.6 and 0.3 g/cc. Anembodiment of the invention is one, any or all of prior embodiments inthis paragraph up through the third embodiment in this paragraph whereinthe apparent bulk density is between 0.6 and 0.5 g/cc. An embodiment ofthe invention is one, any or all of prior embodiments in this paragraphup through the third embodiment in this paragraph wherein the mediandiameter is between 1.8 mm and 2.2 mm. An embodiment of the invention isone, any or all of prior embodiments in this paragraph up through thethird embodiment in this paragraph wherein the median diameter isbetween 1.8 mm and 2.2 mm. An embodiment of the invention is one, any orall of prior embodiments in this paragraph up through the thirdembodiment in this paragraph wherein the apparent bulk density isbetween 0.57 to 0.52 g/cc. An embodiment of the invention is one, any orall of prior embodiments in this paragraph up through the thirdembodiment in this paragraph wherein the median diameter is 1.8 mm. Anembodiment of the invention is one, any or all of prior embodiments inthis paragraph up through the third embodiment in this paragraph whereinthe apparent bulk density is 0.57 g/cc. An embodiment of the inventionis one, any or all of prior embodiments in this paragraph up through thethird embodiment in this paragraph wherein the catalyst has mono-modalporous distribution. An embodiment of the invention is one, any or allof prior embodiments in this paragraph up through the third embodimentin this paragraph wherein, the first component is platinum, the secondcomponent is potassium, and the third component is tin. An embodiment ofthe invention is one, any or all of prior embodiments in this paragraphup through the third embodiment in this paragraph wherein the support isselected from the group consisting of silica, alumina, silica-alumina, azeolite, a non-zeolitic molecular sieve, titania, zirconia and mixturesthereof. An embodiment of the invention is one, any or all of priorembodiments in this paragraph up through the third embodiment in thisparagraph wherein the support is selected from the group consisting oftheta-alumina, gamma-alumina, eta-alumina, delta-alumina, and mixturesthereof. An embodiment of the invention is one, any or all of priorembodiments in this paragraph up through the third embodiment in thisparagraph wherein the catalyst has an effective carbon dioxidediffusivity at 10° C. of at least 1.6×10⁻⁶ m²/sec. An embodiment of theinvention is one, any or all of prior embodiments in this paragraph upthrough the third embodiment in this paragraph wherein the noble metalis in an amount between 0.01 wt. % and 5 wt. % based on the totalweight. An embodiment of the invention is one, any or all of priorembodiments in this paragraph up through the third embodiment in thisparagraph wherein the second component is in an amount between 0.7 wt. %and 1.5 wt. % based on the total weight. An embodiment of the inventionis one, any or all of prior embodiments in this paragraph up through thethird embodiment in this paragraph wherein the third component is in anamount between 0.01 wt. % and 5 wt. % based on the total weight.

A fourth embodiment of the invention is a process for the selectiveconversion of hydrocarbons, the process comprising contacting ahydrocarbon at selective conversion conditions with a catalyticcomposite a first component selected from the group consisting of GroupVIII noble metals and mixtures thereof, a second component selected fromthe group consisting of alkali metals or alkaline-earth metals andmixtures thereof, and a third component selected from the groupconsisting of tin, germanium, lead, indium, gallium, thallium andmixtures thereof and a support forming a spherical catalyst particlewith a median diameter between 1.6 mm and 2.5 mm and an apparent bulkdensity between 0.6 and 0.3 g/cc. An embodiment of the invention is one,any or all of prior embodiments in this paragraph up through the fourthembodiment in this paragraph wherein the hydrocarbon comprises propane,and wherein the selective conversion comprises dehydrogenation. Anembodiment of the invention is one, any or all of prior embodiments inthis paragraph up through the fourth embodiment in this paragraphwherein the median diameter of the catalyst is 1.8 mm and wherein theapparent bulk density is 0.57 g/cc.

A fifth embodiment of the invention is a process for the regeneration acatalyst used for a selective conversion of hydrocarbons, the processcomprising removing coke from a catalytic composite a first componentselected from the group consisting of Group VIII noble metals andmixtures thereof, a second component selected from the group consistingof alkali metals or alkaline-earth metals and mixtures thereof, and athird component selected from the group consisting of tin, germanium,lead, indium, gallium, thallium and mixtures thereof and a supportforming a spherical catalyst particle with a median diameter between 1.6mm and 2.5 mm and an apparent bulk density between 0.6 and 0.3 g/cc. Anembodiment of the invention is one, any or all of prior embodiments inthis paragraph up through the fifth embodiment in this paragraph whereinthe median diameter of the catalyst is 1.8 mm and wherein the apparentbulk density is 0.57 g/cc.

A sixth embodiment of the invention is a process for a selectiveconversion of hydrocarbons, the catalyst comprising a first componentselected from the group consisting of Group VIII noble metals andmixtures thereof, a second component selected from the group consistingof alkali metals or alkaline-earth metals and mixtures thereof, and athird component selected from the group consisting of tin, germanium,lead, indium, gallium, thallium and mixtures thereof; and a supportforming a spherical catalyst particle with an average pore diameterbetween 200 to 350 Angstroms, a porosity of at least 75% and an apparentbulk density between 0.60 and 0.3 g/cc. An embodiment of the inventionis one, any or all of prior embodiments in this paragraph up through thesixth embodiment in this paragraph wherein the apparent bulk density isbetween 0.60 and 0.5 g/cc. An embodiment of the invention is one, any orall of prior embodiments in this paragraph up through the fifthembodiment in this paragraph wherein the apparent bulk density isbetween 0.57 to 0.52 g/cc. An embodiment of the invention is one, any orall of prior embodiments in this paragraph up through the sixthembodiment in this paragraph wherein the wherein the apparent bulkdensity is 0.57 g/cc. An embodiment of the invention is one, any or allof prior embodiments in this paragraph up through the sixth embodimentin this paragraph wherein the apparent bulk density is between 0.57 to0.52 g/cc. An embodiment of the invention is one, any or all of priorembodiments in this paragraph up through the sixth embodiment in thisparagraph wherein the average pore diameter is between 240 to 280Angstroms. An embodiment of the invention is one, any or all of priorembodiments in this paragraph up through the sixth embodiment in thisparagraph wherein the catalyst has mono-modal porous distribution. Anembodiment of the invention is one, any or all of prior embodiments inthis paragraph up through the sixth embodiment in this paragraphwherein, the first component is platinum, the second component ispotassium, and the third component is tin. An embodiment of theinvention is one, any or all of prior embodiments in this paragraph upthrough the sixth embodiment in this paragraph wherein the support isselected from the group consisting of silica, alumina, silica-alumina, azeolite, a non-zeolitic molecular sieve, titania, zirconia and mixturesthereof. An embodiment of the invention is one, any or all of priorembodiments in this paragraph up through the sixth embodiment in thisparagraph wherein the support is selected from the group consisting oftheta-alumina, gamma-alumina, eta-alumina, delta-alumina, and mixturesthereof. An embodiment of the invention is one, any or all of priorembodiments in this paragraph up through the sixth embodiment in thisparagraph wherein the catalyst has an oxygen effective diffusivity at480° C. of at least 1.5×10⁻⁷ m²/s. An embodiment of the invention isone, any or all of prior embodiments in this paragraph up through thesixth embodiment in this paragraph wherein the noble metal is in anamount between 0.01 wt. % and 5 wt. % based on the total weight. Anembodiment of the invention is one, any or all of prior embodiments inthis paragraph up through the sixth embodiment in this paragraph whereinthe second component is in an amount between 0.7 wt. % and 1.5 wt. %based on the total weight. An embodiment of the invention is one, any orall of prior embodiments in this paragraph up through the sixthembodiment in this paragraph wherein the third component is in an amountbetween 0.01 wt. % and 5 wt. % based on the total weight. An embodimentof the invention is one, any or all of prior embodiments in thisparagraph up through the sixth embodiment in this paragraph wherein thecatalyst has a median diameter between 1.8 mm and 2.2 mm.

A seventh embodiment of the invention is a process for regenerating acatalyst used for a selective conversion of hydrocarbons, the processcomprising removing coke from a catalytic composite a first componentselected from the group consisting of Group VIII noble metals andmixtures thereof, a second component selected from the group consistingof alkali metals or alkaline-earth metals and mixtures thereof, and athird component selected from the group consisting of tin, germanium,lead, indium, gallium, thallium and mixtures thereof and a supportforming a support forming a spherical catalyst particle with an averagepore diameter between 200 to 350 Angstroms, a porosity of at least 80%and an apparent bulk density between 0.60 and 0.3 g/cc. An embodiment ofthe invention is one, any or all of prior embodiments in this paragraphup through the seventh embodiment in this paragraph wherein the apparentbulk density is between 0.60 and 0.5 g/cc. An embodiment of theinvention is one, any or all of prior embodiments in this paragraph upthrough the seventh embodiment in this paragraph wherein the averagepore diameter is between 240 to 280 Angstroms.

An eighth embodiment of the invention is a process for the selectiveconversion of hydrocarbons, the process comprising contacting ahydrocarbon at selective conversion conditions with a catalyticcomposite a first component selected from the group consisting of GroupVIII noble metals and mixtures thereof, a second component selected fromthe group consisting of alkali metals or alkaline-earth metals andmixtures thereof, and a third component selected from the groupconsisting of tin, germanium, lead, indium, gallium, thallium andmixtures thereof and a support forming a spherical catalyst particlewith an average pore diameter between 200 to 350 Angstroms, a porosityof at least 80% and an apparent bulk density between 0.60 and 0.3 g/cc.An embodiment of the invention is one, any or all of prior embodimentsin this paragraph up through the eighth embodiment in this paragraphwherein the apparent bulk density is between 0.60 and 0.5 g/cc.

Without further elaboration, it is believed that using the precedingdescription that one skilled in the art can utilize the presentinvention to its fullest extent and easily ascertain the essentialcharacteristics of this invention, without departing from the spirit andscope thereof, to make various changes and modifications of theinvention and to adapt it to various usages and conditions. Thepreceding preferred specific embodiments are, therefore, to be construedas merely illustrative, and not limiting the remainder of the disclosurein any way whatsoever, and that it is intended to cover variousmodifications and equivalent arrangements included within the scope ofthe appended claims.

In the foregoing, all temperatures are set forth in degrees Celsius and,all parts and percentages are by weight, unless otherwise indicated.

While at least one exemplary embodiment has been presented in theforegoing detailed description of the invention, it should beappreciated that a vast number of variations exist. It should also beappreciated that the exemplary embodiment or exemplary embodiments areonly examples, and are not intended to limit the scope, applicability,or configuration of the invention in any way. Rather, the foregoingdetailed description will provide those skilled in the art with aconvenient road map for implementing an exemplary embodiment of theinvention, it being understood that various changes may be made in thefunction and arrangement of elements described in an exemplaryembodiment without departing from the scope of the invention as setforth in the appended claims and their legal equivalents.

What is claimed is:
 1. A process for reducing a time associated withregenerating a catalyst used for a selective conversion of hydrocarbons,the process comprising: removing coke from a catalyst comprising a firstcomponent selected from the group consisting of Group VIII noble metalsand mixtures thereof, a second component selected from the groupconsisting of alkali metals or alkaline-earth metals and mixturesthereof, a third component selected from the group consisting of tin,germanium, lead, indium, gallium, thallium and mixtures thereof, andwherein the time associated with regenerating the catalyst is reduced atleast 10% compared to a theoretical time for regenerating the catalystby the catalyst further comprising a support forming a catalyst particlewith a median diameter between 1.6 mm and 2.5 mm and an apparent bulkdensity between 0.6 and 0.3 g/cc.
 2. The process of claim 1 wherein theapparent bulk density is between 0.6 and 0.5 g/cc.
 3. The process ofclaim 2 wherein the median diameter is between 1.8 mm and 2.2 mm.
 4. Theprocess of claim 1 wherein the median diameter is between 1.8 mm and 2.2mm.
 5. The process of claim 4 wherein the apparent bulk density isbetween 0.57 to 0.52 g/cc.
 6. The process of claim 1 wherein the mediandiameter is 1.8 mm.
 7. The process of claim 6 wherein the apparent bulkdensity is 0.57 g/cc.
 8. The process of claim 1 wherein the catalyst hasmono-modal porous distribution.
 9. The process of claim 1 wherein thecatalyst has bi-modal porous distribution.
 10. The process of claim 1wherein, the first component is platinum, the second component ispotassium, and the third component is tin.
 11. The process of claim 1wherein the support is selected from the group consisting of silica,alumina, silica-alumina, a zeolite, a non-zeolitic molecular sieve,titania, zirconia and mixtures thereof.
 12. The process of claim 11wherein the support is selected from the group consisting oftheta-alumina, gamma-alumina, eta-alumina, delta-alumina, and mixturesthereof.
 13. The process of claim 1 wherein the noble metal is in anamount between 0.01 wt. % and 5 wt. % based on the total weight.
 14. Theprocess of claim 1 wherein the second component is in an amount between0.7 wt. % and 1.5 wt. % based on the total weight.
 15. The process ofclaim 1 wherein the third component is in an amount between 0.01 wt. %and 5 wt. % based on the total weight.
 16. The process of claim 1wherein the catalyst particle is spherical.
 17. The process of claim 1wherein the catalyst has an oxygen effective diffusivity at 480° C. ofat least 1.5×10⁻⁷ m²/s.
 18. The process of claim 1 wherein the catalystparticle has an effective carbon dioxide diffusivity at 10° C. of atleast 1.6×10⁻⁶ m²/sec.
 19. A process for regenerating a catalyst usedfor a selective conversion of hydrocarbons, the process comprising:removing coke from a catalytic composite a first component selected fromthe group consisting of Group VIII noble metals and mixtures thereof, asecond component selected from the group consisting of alkali metals oralkaline-earth metals and mixtures thereof, and a third componentselected from the group consisting of tin, germanium, lead, indium,gallium, thallium and mixtures thereof and a support forming a catalystparticle with a median diameter between 1.6 mm and 2.5 mm and anapparent bulk density between 0.6 and 0.3 g/cc, and wherein a timeassociated with removing coke from the catalytic composite is lower thana calculated time to remove coke from the catalytic composite.
 20. Theprocess of claim 19 wherein the time associated with removing coke fromthe catalytic composite is at least 10% lower than a calculated time toremove coke from the catalytic composite.